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555 Timer Question

Discussion in 'Electronic Basics' started by semaj, Dec 22, 2005.

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  1. semaj

    semaj Guest

    I am interested in setting up a 555 timer for extremely long pulse
    times, 15 minutes. Also, an AC output, one positive square wave pulse
    followed by one negative, etc. How much of a problem is leakage from
    capacitors with such extremely long delays? I have to make this simple.
    Thanks for your time. Any help would be appreciated.
     
  2. Dave

    Dave Guest

    This question just came out in January 2006 Nuts & Volts (www.nutsvolts.com)
    issue, page 13. This article is not on their website yet so if you want me
    to I can draw up the schematic they have in the magazine. They use a 4060
    ripple counter IC, resistors (4.7M, 330K, 1K), pot (100K), 68uF cap, 2N3904,
    1N4001 and a relay... fairly simple circuit....

    From the article :

    "The 4060 includes an oscillator whose frequency is set by two resistors and
    a single capacitor. When the oscillators frequency is at 18.2 Hz, the Q14
    output (pin 3 of the 4060) will toggle on and off every 15 minutes... the
    100K pot is for fine tuning the timer."

    The relay will control what you want on or off...

    This should take care of the "timing" issue you are needing...

    Hope this helps a little or sparks an idea...

    Dave
     
  3. John Fields

    John Fields Guest

     
  4. Dave

    Dave Guest

    Here is the schematic... http://www.audiopulse.net/15_minute_timer.jpg

    Like I said, pretty simple...

    On your AC output... are you meaning "one positive square wave pulse" for 15
    minutes?? (positive voltage for 15 minutes) Then a negative square pulse
    for the next 15 minutes??? (negative voltage for 15 minutes) ???

    Need to explain this more.......

    Dave
     
  5. semaj

    semaj Guest

    Thanks very much! I will look at it in just a moment.
    Yes, that's what I mean. I am not fluent in electronics (Sorry!), but I
    can build simple circuits from a schematic.
    I am also curious if the audio output from the headphone jack of a CD
    player can be inputted to the circuit and modulate these pulses. Is
    that possible?
    Thanks very much for your time. I appreciate it.
     
  6. Dave

    Dave Guest


    What kind of voltage are you wanting to use?? 12v - 9v - 120v?? on the
    outputs? What are you wanting to run?


    Dave
     
  7. semaj

    semaj Guest

    9 volts.
     
  8. semaj

    semaj Guest

    This 4060 timer chip, is it also known as M54HC4060? Thanks.
     
  9. John Fields

    John Fields Guest

     
  10. DSallee

    DSallee Guest

    Not exactly sure... the article only says "4060 Ripple Counter"

    Here is an update on the schematic... I added some relays to control the
    output switching...

    This should work.. no guarantees because I haven't built it to make sure it
    would work :) .. logically and on paper it should...

    I have made 2 schematics, one showing the positive cycle
    www.audiopulse.net/timer1.jpg and one showing the negative cycle...
    www.audiopulse.net/timer2.jpg

    You will notice that with each 15 minute pulse of the 1st relay, the other 2
    relays will switch polarities on the output you are needing switched...
    giving you the cycling you wanted... +9v for 5 minutes then -9v for 15
    minutes then back to +9v for 15 minutes and so on....

    Hope this helps
    Dave
     
  11. John Fields

    John Fields Guest

    Why make it so hard?

    Just use the relay connected to the transistor connected to Q14 of
    the 4060:


    +V
    | +9V -9V
    +--------+ | |
    |A | O--> /<--+
    [DIODE] [COIL] - - - -/
    | | O
    +--------+ |
    | +----------> +/-V OUT
    C
    4060 Q14>--[R]--B
    E
    |
    +--------------------> GND
     
  12. DSallee

    DSallee Guest

    Hey John,

    Thanks for the input as I am also learning... :)

    I'm a little confused on how this would work? With how you have it, wouldn't
    you have to supply a -9v so it would switch between the +9v and -9v with
    just the one relay??

    Sorry if this is elementary but my "little" brain only came up with what I
    had with the relays... LOL Can't seem to comprehend what you are
    describing...

    The top 3 voltages ( +V , +9 and -9) in your drawing above, are those the
    "supplied" voltages??

    Dave
     
  13. John Fields

    John Fields Guest

    ---
    Yes. If the + and -9V were batteries they'd would look like this:
    (View in Courier) +V is just the voltage to operate the relay, and
    if it were a 9V relay the + 9V could be used to energize it during
    the times +9V was supposed to be the circuit's output.


    +V
    | +9V -9V
    +--------+ | |
    |A | O--> /<--O
    [DIODE] [COIL] -|- - -/ |
    | | | O |
    +--------+ | | |
    | | +-----|----> +/-V OUT
    C |+ |
    4060 Q14>--[R]--B [BT1] [BT2]
    E | |+
    | | |
    +----+----------+----> GND
     
  14. DSallee

    DSallee Guest


    Thanks for clearing that up John... I was taking it (what they was wanting)
    as using just one supplied voltage of +9v... the relays would then do the
    switching from neg. to pos. ...

    Either one would work I guess, yours is much simpler but requires 2 separate
    supplied voltages...

    Thanks again John

    Dave

    Oh, BTW.. if they were to use the 3 relays as in my design... would the 2
    other relays need diodes also?? I missed that before I uploaded it....

    Dave
     
  15. John Fields

    John Fields Guest

     
  16. DSallee

    DSallee Guest

    Thanks John...
    Yea, my hostings server went down I guess... still not up.. grrr...

    Anyway, they were coming off of the 1st relay so I guess they don't need
    them...

    Thanks again John..
    Dave
     
  17. John Fields

    John Fields Guest

    ---
    It depends on what he's going to do with the output signal. Your
    way requires a floating load, (that is, the load can't be grounded)
    while using two supplies lets it be grounded if necessary.

    BTW, I went over to that page again (it was up this time) and it
    struck me that by using a DPDT relay as the relay being switched by
    the transistor and your circuitry to do the polarity reversal into
    the load, both of the other relays could be eliminated, like this:



    +9V
    |
    +----+-------------------------+
    | | |
    +--------+ | |
    |A | O--> /<--O-+-O--> /<--O
    [DIODE] [COIL] - - - -/- - - | - - - /
    | | O | O
    +--------+ | | |
    | | | +--------->OUT
    C | |
    4060 Q14>--[R]--B +------------------------>OUT
    E |
    | |
    +-----------------+
    |
    GND

    :)
     
  18. John Fields

    John Fields Guest

    ---
    The cathode of the diode should go to +9V:

    +9V
    |
    +----+-------------------------+
    | | |
    +--------+ | |
    |K | O--> /<--O-+-O--> /<--O
    [DIODE] [COIL] - - - -/- - - | - - - /
    | | O | O
    +--------+ | | |
    | | | +--------->OUT
    C | |
    4060 Q14>--[R]--B +------------------------>OUT
    E |
    | |
    +-----------------+
    |
    GND
     
  19. DSallee

    DSallee Guest

    Now see, I knew there was a simpler way to make the one I designed.. LOL I
    just couldn't come up with it... The thought of using 1 DPDT relay had
    crossed my mind but I wasn't seeing how it would work...

    Now I do...

    Thanks John for helping me out ... I'm planning on building a few projects
    of my own during the next year.. I graduate in December 2006 .. will be
    getting CET certified, J-Standard certified, A+ certified, FCC licensed and
    certified...

    I will probably be asking you some design questions in the future, If it's
    ok?

    I know I can just go out and buy these things but I think I would learn more
    and have more satisfaction if I attempt to build them... Here is a list of
    things I'm going to ATTEMPT to build.. LOL

    Power Supply (fixed plus variable voltages)
    DMM
    Freq. Counter
    Soldering station
    Small Power Amp (stereo)
    AM/FM Radio
    Function Gen.

    just to start with...

    Thanks again for your help... looking forward to talking to you again...

    Dave
     
  20. John Fields

    John Fields Guest

     
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